The use of solar water-heaters for various uses is well-known. They are utilized in many applications, including, but not limited to, swimming pool, supplying residential hot water, etc. They are typically installed on roofs, which, inter alia, provides a location with minimal obstacles to solar radiation impinging thereon.
A typical system comprises one or more thin tubes carrying water to be heated. The tubes are positioned so as to be exposed to solar radiation. During daylight hours, water which flows through the tubes is heated by the sunlight. The flow may be forced (e.g., by employing a pump or other suitable apparatus), and/or the system may be designed to take advantage of natural properties of water (e.g., the difference in specific gravities between water of different temperatures) to induce the flow.